Formation of plastic containers by injection blow molding can be achieved by the utilization of either one of two distinct injection blow mold processes.
One of the processes features the injection formation of a preform with the preform being allowed to cool to room temperature. The preform can then be stored or can be sent immediately to a blow molding station where the formed preform will be blown to the shape of the article desired. Prior to the blow molding the preform has to be heated back up to its blow molding temperature. This process is disadvantageous in that it has a high energy requirement since the preform must be heated from room temperature up to the blow molding temperature.
The high energy requirements of the above-described process can be overcome by a process which injection forms a preform and passes it, while it still is in a heated condition, to a blow station where it is blown. Optional temperature treating stations may be placed between the injection station and the blow molding station to program the preform to achieve desired shapes and wall thicknesses for the final blown product. Since the preform is not allowed to cool back to room temperature the heat requirements of such a process are considerably lower than the first described process.
It is therefore an object of this invention to provide an apparatus which is capable of preforming the second described injection blow mold process and which allows for highly accurate heat treatment of the preform prior to blow molding with minimum energy consumption and with a short cycle time.